Derivatized guar gums, such as carboxyl methyl guar gum, hydroxypropyl guar gum, and hydroxypropyl trimethylammonium guar gum, are commercially available materials used in a variety of applications, including as ingredients in personal care compositions, and are typically made by a “water-splits” process, wherein material, known as guar “splits”, derived from guar seeds undergoes reaction with a derivatizing agent in an aqueous medium.
Borax (sodium tetra borate) is commonly used as a processing aid in the reaction step of the water-splits process to partially crosslink the surface of the guar splits and thereby reduces the amount of water absorbed by the guar splits during washing. The borate crosslinking takes place under alkaline conditions and is reversible allowing the product to hydrate under acidic conditions. Maintaining the moisture content of the derivatized splits at a relatively low level, typically a moisture content of less than or equal to about 90 percent by weight, simplifies handling and milling of the washed derivatized splits. In the absence of crosslinking, the moisture content of washed derivatized splits is relatively high and handling and further processing of the high moisture content splits is difficult.
However, due to regulatory concerns regarding the boron content of materials used in personal care applications, it has now become desirable to make derivatized guar without using any boron-containing crosslinker.
What is needed is an economically attractive approach to controlling water content of washed cationic guar splits, without requiring that the cationic guar splits first be crosslinked.